Climate Change and Maine’s Forests: What we Know and

Don’t Know

Lloyd C Irland The Irland Group and University of Maine

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Contents

• The Forest and the Trees

– Quick tour of Maine forest geography

• Climate and Vegetation

• “A Bumpy Path”: Example of Moosehead Lake

• Concerns for 2100

• What should we do?

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Moosehead L.

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Climate and Vegetation

• GCMs model huge “Boxes” 200X300 km

• Climate effects on vegetation not always clear – Seasonal regimes not averages

– Temps rainfall and PET; snow and snowfree seasons; fogs

• Temps will increase most at winter minima

• Temp limits on ranges still uncertain

• Extremes may be more important than averages

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Climate/ veg…

• Effects on pests and invasives still under study

• Some species very long-lived

• How will climate affect regeneration competitive status?

• Climate vs other drivers

– Bambi, etc.

• Ecosystems /veg. Types do not migrate as units

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Trees Respond to Climate with Very Long Lag Times

• Current Vegetation is not at equilibrium with soils/climate –Multiple disequilibria

• White pine, sugar maple, hemlock can live 400 yrs +

• Regen. present in understories; can endure a long time

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Multiple Factors/Stressors

• Deer herbivory

• “Bugs and Crud” – esp. introduced

• Invasives taking over understories

• Logging & land use conversions

• Nitrogen saturation

• All of these confound detecting a footprint of past climate change and predicting future

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Maine in particular

• In midst of a tension zone or ecotone between –Boreal vegetation/climates

– Temperate hardwoods

• Transition zone –Has its own characteristic species: hemlock,

white pine

• Topo/ Ocean frontage effects

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Drought?

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Climate regime change: Fire Seasons -- PDSI

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Diff betw. first and last decades, 18.9 days!

Isn’t it Growing Season?

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Phenology: plant life events. Here, from Harvard Forest by John O’Keefe.

Some likely Changes

• Not the CHANGE in climate that’s scary, it’s the RATE of Change

• Stress on range/ vigor of sugar maple

• Stress on subalpine/alpine ecosystems

• Increased incidence of weather extremes? – Saxby’s Gale; Hurricane Sandy ‘38 Hurricane

– ‘47 Drought and fires

• Steady spread of already established invasives, e.g. EAB; HWA;

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Model Results -- Sobering

GTR NRS-999, p. 18.

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What Manomet (2014)Thinks – A more measured view

*Three ecosystems had the highest percentage of high-vulnerability species: Alpine, Montane Forest, and Peatlands. *More than 50% of the species in five early successional and other ecosystems greatly influenced by human activity (e.g., agriculture) had low vulnerability. *The most vulnerable habitats and natural communities include alpine and montane systems, peatlands, northern rivershores, spruce flats, and cedar lowlands. *Coastal and aquatic systems are considered at least moderately vulnerable by all assessments. *Northern forest types also are moderately vulnerable, while oak-pine forests and barrens are likely to remain stable or expand. -- Whitman et al 2014 p. 2

Bottom Line

• Other effects/footprints of climate change are likely to become evident far sooner than do clear, measurable effects on forests.

• Perhaps most important effects we do not yet suspect, or are not measuring!

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Citizen Science • A huge opportunity for Citizen Science here

• Immense amount of relevant data is in file boxes, on paper, not accessible to computers.

• MFS Entomology Lab, records of experiment stations, apple orchards, airports, farmer journals, who knows what else.

• Awaits mining through, compilation, electronic capture, and analysis.

• There aren’t enough grad students to do all this!

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When we know for sure it will be too late!

What to do? • Management only affects 3-4% of forest area

each year.

– Less in So. Maine

• Only planting 8,000 acres or so annually

• So, how do we affect the forest????

– Exactly what do we do?

– Most past discussions rehash generalities

• When you have a costly, complex, uncertain problem, you need --

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• Irland’s First Law of Management:

• Get Started!

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Tension Between Goals

• Grow ‘em longer - store more carbon – vs

• Reduce stocking levels to improve vigor and resilience

• OR

• Keep lots of late-successional for biodiversity – Vs

• Cut frequently, use short rotations, to speed adaptation

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In Closing

• Climate is clearly Changing and will continue to change

• We cannot know with any precision how Maine’s forests will change -- but they will

• Hard to develop clear recommendations for land managers

• One thing is Clear; Society needs to Decarbonize!

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Thanks for your time and attention

• Questions?

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Ponderosa pine, New Mexico